scholarly journals Essential Immunoregulatory Role for BCAP in B Cell Development and Function

2002 ◽  
Vol 195 (5) ◽  
pp. 535-545 ◽  
Author(s):  
Tetsuo Yamazaki ◽  
Kiyoshi Takeda ◽  
Kumiko Gotoh ◽  
Hiroshi Takeshima ◽  
Shizuo Akira ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
Humoral Immune ◽  
Humoral Immune Responses ◽  
Phosphoinositide 3 Kinase ◽  
And Function ◽  
B Cell Deficiency

BCAP was recently cloned as a binding molecule to phosphoinositide 3-kinase (PI3K). To investigate the role of BCAP, mutant mice deficient in BCAP were generated. While BCAP-deficient mice are viable, they have decreased numbers of mature B cells and B1 B cell deficiency. The mice produce lower titers of serum immunoglobulin (Ig)M and IgG3, and mount attenuated responses to T cell–independent type II antigen. Upon B cell receptor cross-linking, BCAP-deficient B cells exhibit reduced Ca2+ mobilization and poor proliferative responses. These findings demonstrate that BCAP plays a pivotal immunoregulatory role in B cell development and humoral immune responses.

Distinct roles of BCNP1 in B-cell development and activation

2019 ◽  
Vol 32 (1) ◽  
pp. 17-26
Author(s):  
Rongjian Hong ◽  
Nannan Lai ◽  
Ermeng Xiong ◽  
Rika Ouchida ◽  
Jiping Sun ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
Cross Linking ◽  
Humoral Immune ◽  
Humoral Immune Responses ◽  
B Cell Maturation

Abstract B-cell novel protein 1 (BCNP1) has recently been identified as a new B-cell receptor (BCR) signaling molecule but its physiological function remains unknown. Here, we demonstrate that mice deficient in BCNP1 exhibit impaired B-cell maturation and a reduction of B-1a cells. BCNP1-deficient spleen B cells show enhanced survival, proliferation and Ca2+ influx in response to BCR cross-linking as compared with wild-type spleen B cells. Consistently, mutant B cells show elevated phosphorylation of SYK, B-cell linker protein (BLNK) and PLCγ2 upon BCR cross-linking. In vivo, BCNP1-deficient mice exhibit enhanced humoral immune responses to T-independent and T-dependent antigens. Moreover, aged mutant mice contain elevated levels of serum IgM and IgG3 antibodies and exhibit polyclonal and monoclonal B-cell expansion in lymphoid organs. These results reveal distinct roles for BCNP1 in B-cell development, activation and homeostasis.

scholarly journals Germline-activating mutations in PIK3CD compromise B cell development and function

2018 ◽  
Vol 215 (8) ◽  
pp. 2073-2095 ◽  
Author(s):  
Danielle T. Avery ◽  
Alisa Kane ◽  
Tina Nguyen ◽  
Anthony Lau ◽  
Akira Nguyen ◽  
...  
Keyword(s):  
B Cell ◽  
Cytidine Deaminase ◽  
Pathogenic Mutation ◽  
Gene Signature ◽  
Cell Development ◽  
B Cell Development ◽  
Humoral Immune ◽  
Humoral Immune Responses ◽  
Class Switch ◽  
And Function

Gain-of-function (GOF) mutations in PIK3CD, encoding the p110δ subunit of phosphatidylinositide 3-kinase (PI3K), cause a primary immunodeficiency. Affected individuals display impaired humoral immune responses following infection or immunization. To establish mechanisms underlying these immune defects, we studied a large cohort of patients with PIK3CD GOF mutations and established a novel mouse model using CRISPR/Cas9-mediated gene editing to introduce a common pathogenic mutation in Pik3cd. In both species, hyperactive PI3K severely affected B cell development and differentiation in the bone marrow and the periphery. Furthermore, PI3K GOF B cells exhibited intrinsic defects in class-switch recombination (CSR) due to impaired induction of activation-induced cytidine deaminase (AID) and failure to acquire a plasmablast gene signature and phenotype. Importantly, defects in CSR, AID expression, and Ig secretion were restored by leniolisib, a specific p110δ inhibitor. Our findings reveal key roles for balanced PI3K signaling in B cell development and long-lived humoral immunity and memory and establish the validity of treating affected individuals with p110δ inhibitors.

scholarly journals The intramembrane protease SPPL2a promotes B cell development and controls endosomal traffic by cleavage of the invariant chain

2012 ◽  
Vol 210 (1) ◽  
pp. 41-58 ◽  
Author(s):  
Janna Schneppenheim ◽  
Ralf Dressel ◽  
Susann Hüttl ◽  
Renate Lüllmann-Rauch ◽  
Michael Engelke ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Surface Expression ◽  
Cell Development ◽  
Significant Loss ◽  
B Cell Development ◽  
Invariant Chain ◽  
Intramembrane Proteolysis ◽  
Humoral Immune

Regulated intramembrane proteolysis is a central cellular process involved in signal transduction and membrane protein turnover. The presenilin homologue signal-peptide-peptidase-like 2a (SPPL2a) has been implicated in the cleavage of type 2 transmembrane proteins. We show that the invariant chain (li, CD74) of the major histocompatability class II complex (MHCII) undergoes intramembrane proteolysis mediated by SPPL2a. B lymphocytes of SPPL2a−/− mice accumulate an N-terminal fragment (NTF) of CD74, which severely impairs membrane traffic within the endocytic system and leads to an altered response to B cell receptor stimulation, reduced BAFF-R surface expression, and accumulation of MHCII in transitional developmental stage T1 B cells. This results in significant loss of B cell subsets beyond the T1 stage and disrupted humoral immune responses, which can be recovered by additional ablation of CD74. Hence, we provide evidence that regulation of CD74-NTF levels by SPPL2a is indispensable for B cell development and function by maintaining trafficking and integrity of MHCII-containing endosomes, highlighting SPPL2a as a promising pharmacological target for depleting and/or modulating B cells.

scholarly journals Distinct Roles of Phosphoinositide-3 Kinase and Phospholipase Cγ2 in B-Cell Receptor-Mediated Signal Transduction

2006 ◽  
Vol 26 (1) ◽  
pp. 88-99 ◽  
Author(s):  
Xuezhi Dai ◽  
Yuhong Chen ◽  
James Schuman ◽  
Zichun Hua ◽  
John W. Adamson ◽  
...  
Keyword(s):  
Signal Transduction ◽  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
B Cell Receptor ◽  
Bcr Signaling ◽  
Phosphoinositide 3 Kinase ◽  
Cell Transition

ABSTRACT During B-cell receptor (BCR) signaling, phosphoinositide-3 kinase (PI3K) is thought to function upstream of phospholipase Cγ2 (PLCγ2). PLCγ2 deficiency specifically impedes transitional type 2 (T2) to follicular (FO) mature B-cell transition. Here, we demonstrate that PI3K deficiency specifically impaired T2-to-FO mature B-cell transition and marginal zone B-cell development. Furthermore, we investigated the functional relationship between PI3K and PLCγ2 using PI3K−/−, PLCγ2−/−, and PI3K−/− PLCγ2−/− B cells. Interestingly, PLCγ2 deficiency had no effect on BCR-mediated PI3K activation, whereas PI3K deficiency only partially blocked activation of PLCγ2. Moreover, whereas PI3K−/− PLCγ2−/− double deficiency did not affect hematopoiesis, it resulted in embryonic lethality. PI3K−/− PLCγ2−/− fetal liver cells transplanted into B-cell null JAK3−/− mice failed to restore development of peripheral B cells and failed to progress through early B-cell development at the pro-B- to pre-B-cell transition, a more severe phenotype than was observed with either PI3K or PLCγ2 single-deficiency B cells. Consistent with this finding, BCR signaling was more severely impaired in the absence of both PI3K and PLCγ2 genes than in the absence of either one alone. Taken together, these results demonstrate that whereas PI3K functions upstream of PLCγ2, activation of PLCγ2 can occur independently of PI3K and that PI3K and PLCγ2 also have distinct functions in BCR signal transduction.

scholarly journals A generalized quantitative antibody homeostasis model: regulation of B-cell development by BCR saturation and novel insights into bone marrow function

2016 ◽  
Author(s):  
József Prechl
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Quantitative Model ◽  
Cell Development ◽  
B Cell Development ◽  
Marginal Zone B Cells ◽  
Humoral Immune ◽  
Narrow Region

In a pair of articles we present a generalized quantitative model for the homeostatic function of clonal humoral immune system. In this first paper we describe the cycles of B-cell expansion and differentiation driven by B-cell receptor engagement.The fate of a B cell is determined by the signals it receives via its antigen receptor at any point of its lifetime. We express BCR engagement as a function of apparent affinity and free antigen concentration, using the range of 10−14 to 10−3 M for both factors. We assume that for keeping their BCR responsive B cells must maintain partial BCR saturation, which is a narrow region defined by [Ag]≈KD. To remain in this region, B cells respond to changes in [Ag] by proliferation or apoptosis and modulate KD by changing BCR structure. We apply this framework to various niches of B-cell development, such as the bone marrow, blood, lymphoid follicles and germinal centers. We propose that clustered B cells in the bone marrow and in follicles present antigen to surrounding B cells by exposing antigen captured on complement and Fc receptors. The model suggests that antigen-dependent selection in the bone marrow results in 1) effector BI cells, which develop in blood as a consequence of the inexhaustible nature of soluble antigens, 2) memory cells that survive in antigen rich niches, identified as marginal zone B cells. Finally, the model implies that memory B cells could derive survival signals from abundant non-cognate antigens.

scholarly journals B Cell Development Is Arrested at the Immature B Cell Stage in Mice Carrying a Mutation in the Cytoplasmic Domain of Immunoglobulin β

2000 ◽  
Vol 193 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Amy Reichlin ◽  
Yun Hu ◽  
Eric Meffre ◽  
Hitoshi Nagaoka ◽  
Shiaoching Gong ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Cytoplasmic Domain ◽  
Cell Development ◽  
Immature Stage ◽  
B Cell Development ◽  
Cell Stage ◽  
And Function

The B cell receptor (BCR) regulates B cell development and function through immunoglobulin (Ig)α and Igβ, a pair of membrane-bound Ig superfamily proteins, each of which contains a single cytoplasmic immunoreceptor tyrosine activation motif (ITAM). To determine the function of Igβ, we produced mice that carry a deletion of the cytoplasmic domain of Igβ (IgβΔC mice) and compared them to mice that carry a similar mutation in Igα (MB1ΔC, herein referred to as IgαΔC mice). IgβΔC mice differ from IgαΔC mice in that they show little impairment in early B cell development and they produce immature B cells that respond normally to BCR cross-linking as determined by Ca2+ flux. However, IgβΔC B cells are arrested at the immature stage of B cell development in the bone marrow and die by apoptosis. We conclude that the cytoplasmic domain Igβ is required for B cell development beyond the immature B cell stage and that Igα and Igβ have distinct biologic activities in vivo.

Loss of IP3 Receptor–Mediated Ca2+ Release in Mouse B Cells Results in Abnormal B Cell Development and Function

2017 ◽  
Vol 199 (2) ◽  
pp. 570-580 ◽  
Author(s):  
Huayuan Tang ◽  
Hong Wang ◽  
Qingsong Lin ◽  
Feifei Fan ◽  
Fei Zhang ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Development ◽  
B Cell Development ◽  
Ip3 Receptor ◽  
And Function

scholarly journals bcl-x exhibits regulated expression during B cell development and activation and modulates lymphocyte survival in transgenic mice.

1996 ◽  
Vol 183 (2) ◽  
pp. 381-391 ◽  
Author(s):  
D A Grillot ◽  
R Merino ◽  
J C Pena ◽  
W C Fanslow ◽  
F D Finkelman ◽  
...  
Keyword(s):  
B Cells ◽  
Transgenic Mice ◽  
B Cell ◽  
Cell Lineage ◽  
Cell Development ◽  
B Cell Development ◽  
Immunoglobulin M ◽  
Protective Mechanism ◽  
And Function ◽  
Peripheral B Cells

We have assessed during B cell development, the regulation and function of bcl-x, a member of the bcl-2 family of apoptosis regulatory genes. Here we show that Bcl-xL, a product of bcl-x, is expressed in pre-B cells but downregulated at the immature and mature stages of B cell development. Bcl-xL but not Bcl-2 is rapidly induced in peripheral B cells upon surface immunoglobulin M (IgM) cross-linking, CD40 signaling, or LPS stimulation. Transgenic mice that overexpressed Bcl-xL within the B cell lineage exhibited marked accumulation of peripheral B cells in lymphoid organs and enhanced survival of developing and mature B cells. B cell survival was further increased by simultaneous expression of bcl-xL and bcl-2 transgenes. These studies demonstrate that Bcl-2 and Bcl-xL are regulated differentially during B cell development and activation of mature B cells. Induction of Bcl-xL after signaling through surface IgM and CD40 appears to provide mature B cells with an additional protective mechanism against apoptotic signals associated with antigen-induced activation and proliferation.

scholarly journals Essential Role of Phospholipase Cγ2 in Early B-Cell Development and Myc-Mediated Lymphomagenesis

2006 ◽  
Vol 26 (24) ◽  
pp. 9364-9376 ◽  
Author(s):  
Renren Wen ◽  
Yuhong Chen ◽  
Li Bai ◽  
Guoping Fu ◽  
James Schuman ◽  
...  
Keyword(s):  
B Cells ◽  
Transgenic Mice ◽  
B Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
B Cell Receptor ◽  
Wild Type ◽  
Interleukin 7

ABSTRACT Phospholipase Cγ2 (PLCγ2) is a critical signaling effector of the B-cell receptor (BCR). Here we show that PLCγ2 deficiency impedes early B-cell development, resulting in an increase of B220+ CD43+ BP-1+ CD24hi pre-BCR+ large pre-B cells. PLCγ2 deficiency impairs pre-BCR-mediated functions, leading to enhanced interleukin-7 (IL-7) signaling and elevated levels of RAGs in the selected large pre-B cells. Consequently, PLCγ2 deficiency renders large pre-B cells susceptible to transformation, resulting in dramatic acceleration of Myc-induced lymphomagenesis. PLCγ2 −/− Eμ-Myc transgenic mice mainly develop lymphomas of B220+ CD43+ BP-1+ CD24hi pre-BCR+ large pre-B-cell origin, which are uncommon in wild-type Eμ-Myc transgenics. Furthermore, lymphomas from PLCγ2 −/− Eμ-Myc transgenic mice exhibited a loss of p27Kip1 and often displayed alterations in Arf or p53. Thus, PLCγ2 plays an important role in pre-BCR-mediated early B-cell development, and its deficiency leads to markedly increased pools of the most at-risk large pre-B cells, which display hyperresponsiveness to IL-7 and express high levels of RAGs, making them prone to secondary mutations and Myc-induced malignancy.

scholarly journals Increased Frequency of Pre–Pro B Cells in the Bone Marrow of New Zealand Black (NZB) Mice: Implications for aDevelopmental Block in B Cell Differentiation

2002 ◽  
Vol 9 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Zhe-Xiong Lian ◽  
Hiroto Kita ◽  
Tomoyuki Okada ◽  
Tom Hsu ◽  
Leonard D. Shultz ◽  
...  
Keyword(s):  
New Zealand ◽  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
B Cell Differentiation ◽  
Differentiation Markers ◽  
Cell Stage

Reductions in populations of both Pre-B cell (Hardy fractions D) and Pro-B cells (Hardy fractions B–C) have been described in association with murine lupus. Recent studies of B cell populations, based on evaluation of B cell differentiation markers, now allow the enumeration and enrichment of other stage specific precursor cells. In this study we report detailed analysis of the ontogeny of B cell lineage subsets in New Zealand black (NZB) and control strains of mice. Our data suggest that B cell development in NZB mice is partially arrested at the fraction A Pre–Pro B cell stage. This arrest at the Pre-Pro B cell stage is secondary to prolonged lifespan and greater resistance to spontaneous apoptosis. In addition, expression of the gene encoding the critical B cell development transcription factor BSAP is reduced in the Pre–Pro B cell stage in NZB mice. This impairment may influence subsequent B cell development to later stages, and thereby accounts for the down-regulation of the B cell receptor componentIgα(mb-1). Furthermore, levels of expression of theRug2, λ5andIgβ(B29) genes are also reduced in Pre–Pro B cells of NZB mice. The decreased frequency of precursor B cells in the Pre–Pro B cell population occurs at the most primitive stage of B cell differentiation.

Sign in / Sign up

Export Citation Format

Share Document